The age-specific pattern of urbanward migration is so well-known that we sometimes lose sight of its significance. One can even go so far as to maintain that the single feature of migrant selectivity that most benefits the receiving urban community is age, because it is related to so many other characteristics. This judgment applies especially to developing countries where the socioeco-nomic differences between age cohorts are often very great. Young adults are, on the average, better educated, even when their community of origin is held constant. This, in turn, will affect their occupational attainment. Most men migrate to large cities before the peak of their work careers, which comes quite young in developing countries. Most men must find manual employment, for which physical vitality is an important requisite. Moreover, the adaptability of individuals to different environments and the willingness to change environments is related to youth. Migration is one way for a young man to escape domination by his parents. If he were to remain in a rural area, he would be more likely to orient his work and family life according to parental and kin considerations.
Men in rural areas, at least on the basis of the Cedral data, are keenly aware of the relationship of age to success in the city. This is clearly indicated in the series of three questions reported in Table 3. In the first question asked of all men, there is a clear inverse relationship between age and responses favoring leaving Cedral. However, 42 percent of men 45-and-over still say "go," reflecting the lack of economic opportunity in Cedral, an area with a long tradition of out-migration. When the question is specified for men older and younger than the respondent the effect of age at migration becomes very pronounced. Overwhelmingly, young men are urged to leave, and this has almost no variation by age of respondent. For the older men, the advice is the opposite, though not as pronounced as for younger men. There is somewhat more variation by age of respondent, but not much.
By their comments the men indicated they were well aware of the way in which age influenced successful adaptation to the city. It is fair to conclude that many men in rural areas are there not particularly because they want to be, but because they correctly perceive that job opportunities in large cities for men over 35 or 40 are quite limited. In large cities of developing countries the supply of unskilled labor invariably exceeds the demand, so employers understandably do not hire older men, especially since they are less educated as a group and have few specialized skills.
Age specificity of migrants holds up remarkably well through space and time, but the sex ratio (speaking here of the adult population) has no such uniformity. At one time there was a belief to this effect. Ravenstein (21, p. 199) stated as one of his laws, "Females are more migratory than males," butThe conclusion to be drawn from this is that if economic opportunity and living conditions in the cities were to be improved, return migration rates would he lower.an, et al. (1 3, Ch. 1). Substantively, Ghana differs from Mexico in the predominantly male rural-urban migration, in the multilingual character of the society, in the existence of polygamy, and